Merge ~xypron/grub:efivarfs into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu

[Heinrich Schuchardt]

efivar: check that efivarfs is writeable

Some UEFI implementations (notably U-Boot) don't implement the
SetVariable() runtime service. On these systems the GRUB installation
must be completed manually. Write a warning in this case but avoid
throwing an error. (LP: #1965288)

Signed-off-by: Heinrich Schuchardt <email address hidden>

Unmerged commits

7db6e17... by Heinrich Schuchardt on 2022-03-21

efivar: check that efivarfs is writeable

Some UEFI implementations (notably U-Boot) don't implement the
SetVariable() runtime service. On these systems the GRUB installation
must be completed manually. Write a warning in this case but avoid
throwing an error. (LP: #1965288)

Signed-off-by: Heinrich Schuchardt <email address hidden>

diff --git a/debian/patches/efivar-check-that-efivarfs-is-writeable.patch b/debian/patches/efivar-check-that-efivarfs-is-writeable.patch
new file mode 100644
index 0000000..93bcf16
--- /dev/null
+++ b/debian/patches/efivar-check-that-efivarfs-is-writeable.patch
@@ -0,0 +1,117 @@
+From 5bf070ddb6cbcc5af3725908a2e092fd02352f4c Mon Sep 17 00:00:00 2001
+From: Heinrich Schuchardt <[e-mail]>
+Date: Fri, 18 Mar 2022 15:21:33 +0100
+Subject: [PATCH 1/1] efivar: check that efivarfs is writeable
+
+Some UEFI implementations (notably U-Boot) don't implement the
+SetVariable() runtime service. On these systems the GRUB installation
+must be completed manually. Write a warning in this case but avoid
+throwing an error.
+
+Signed-off-by: Heinrich Schuchardt <[e-mail]>
+---
+ grub-core/osdep/unix/efivar.c | 81 +++++++++++++++++++++++++++++++++++
+ 1 file changed, 81 insertions(+)
+
+diff --git a/grub-core/osdep/unix/efivar.c b/grub-core/osdep/unix/efivar.c
+index d34df0f70..8a7ee0c94 100644
+--- a/grub-core/osdep/unix/efivar.c
++++ b/grub-core/osdep/unix/efivar.c
+@@ -511,6 +511,79 @@ devices_equal (const_efidp a, const_efidp b)
+   return false;
+ }
+ 
++/**
++ * efivar_is_rw - detect if the efivar file system exists and is writeable
++ *
++ * Return:	true if efivarfs is writeable
++ */
++static bool
++efivar_is_rw (void)
++{
++  const char filename[] = "/proc/self/mounts";
++  int fd;
++  grub_uint64_t size;
++  char *data = NULL, *start, *end, *pos;
++  bool ret = false;
++
++  fd = grub_util_fd_open (filename, GRUB_UTIL_FD_O_RDONLY);
++  if (fd == -1)
++    {
++      grub_util_warn (_("cannot open `%s': %s"), filename, strerror (errno));
++      return 0;
++    }
++
++  /*
++   * /proc/self/mounts does not provide a filesize. So read it into an initial
++   * buffer. If the last byte of the buffer is overwritten, retry with double
++   * the buffer size.
++   */
++  size = 4096;
++  for (;;) {
++    ssize_t s;
++
++    fd = grub_util_fd_open (filename, GRUB_UTIL_FD_O_RDONLY);
++    if (fd == -1)
++      {
++        grub_util_warn (_("cannot open `%s': %s"), filename, strerror (errno));
++        return 0;
++      }
++
++    grub_util_info ("size %ld", size);
++    data = xmalloc (size);
++    grub_memset (data, 0, size);
++    if (!data)
++      {
++        grub_util_warn ("%s", _("out of memory"));
++        goto out;
++      }
++    s = read(fd, data, size);
++    if (s < 0)
++      {
++        grub_util_warn (_("cannot read `%s': %s"), filename, strerror (errno));
++        goto out;
++      }
++    grub_util_fd_close (fd);
++    if (!data[size - 1])
++        break;
++    free(data);
++    size *= 2;
++  }
++
++  start = grub_strstr (data, "efivarfs ");
++  if (!start)
++    goto out;
++  end = grub_strstr (start, "\n");
++  if (!end)
++    goto out;
++  pos = grub_strstr (start, " rw,");
++  if (pos && pos < end)
++    ret = true;
++
++out:
++  grub_free (data);
++  return ret;
++}
++
+ int
+ grub_install_efivar_register_efi (grub_device_t efidir_grub_dev,
+ 				  const char *efidir, const char *efifile_path,
+@@ -528,6 +601,14 @@ grub_install_efivar_register_efi (grub_device_t efidir_grub_dev,
+   int rc;
+   bool is_boot_efi;
+ 
++  /* Check if EFI variable can be written */
++  if (!efivar_is_rw ())
++    {
++      grub_util_warn ("EFI variables cannot be set on this system");
++      grub_util_warn ("You will have to complete the GRUB setup manually");
++      return 0;
++    }
++
+   is_boot_efi = strstr (efidir, "/boot/efi") != NULL;
+   efidir_disk = grub_util_biosdisk_get_osdev (efidir_grub_dev->disk);
+   efidir_part = efidir_grub_dev->disk->partition ? efidir_grub_dev->disk->partition->number + 1 : 1;
+-- 
+2.34.1
+
diff --git a/debian/patches/series b/debian/patches/series
index 7942ada..0a4b388 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -121,3 +121,4 @@ ubuntu-os-prober-auto.patch
 efi-correct-struct-grub_efi_boot_services.patch
 efi-implement-grub_efi_run_image.patch
 fat-fix-listing-the-root-directory.patch
+efivar-check-that-efivarfs-is-writeable.patch